Back in December, I pointed out that Obama had come to what my colleague Bruce Ackerman calls a constitutional moment. If Obama wants health care reform he would have to use reconciliation or push for a reform of Senate filibuster rules. Senate intransigence would lead him to unconventional adaptation if he wanted to salvage his Presidency.

By the end of the health care summit, it was clear that Obama will choosethe less dramatic courseof reconciliation. Doing so, presumably, will expand existing precedents and make it easier to use for major substantive legislation in the future. But using reconciliation in this case will not fundamentally change the dynamic in the Senate, and it will probably not significantly alter constitutional understandings. We will still have polarized parliamentary style parties in a constitutional system that is not designed for parliamentary government because of its super-majority rules and many different veto points. In an important sense, this is the larger structural problem. The party system has mutated in ways that are inconsistent with existing constitutional mechanisms.

If reconciliation fails, Obama will have to attack the filibuster directly. But even if reconciliation succeeds, the constitutional moment will not have been concluded. The worst, I fear, is yet to come.

The 2010 elections will be a referendum on Obama's handling of health care and his use of or failure at reconciliation. However, even if Obama succeeds, there is almost no chance that Obama and the Democrats will pick up seats in this election. They are defending too many marginal districts. For structural reasons, the Democrats are likely to lose around 25 to 30 seats on the average. The question then is whether they lose only to 20 to 25 or 35 to 40.

This means that it is almost impossible for the public to see the results of this election as a mandate for Obama and the Democrats. The Democrats will lose seats, period, and Republicans will interpret this as a sign that they should continue to obstruct on every possible initiative.

Gridlock will get worse, not better following the 2010 elections.

This will put Obama to the test. The next two year cycle will be much the same as the first, with this difference: Obama will be running for reelection, and the economic news will need to become rosier very quickly if he has a chance at gaining a second term.

Therefore the 2012 election will be the real test of Democratic reforms and Democratic will. Obama will be driven to push for measures that he believes necessary to help the economy and secure reelection. Republicans will resist, insisting on tax cuts but no additional spending or government programs. They will be politically stronger, while the Democrats will have even fewer members in the House and Senate.

If Democrats still retain majorities in the House and the Senate, Obama may be forced to push for reform of the Senate rules in order to survive politically. This may precipitate a new round of unconventional adaptation.

If Democrats lose control of one or both Houses of Congress in 2010, however, Obama's task is far more difficult, and he may not be able to try even this. There is no point in trying to end Senate filibusters if one doesn't control the Senate or the House. Therefore we may find ourselves in a showdown situation like the one between Clinton and Gingrich between 1994 and 1996, but this time Republicans, having seen that movie before, will not be as politically inept as they were then.

If Obama loses control of the House or the Senate in 2010, the chances of a reconstructive presidency are significantly reduced, and the chances of Republican resurgence are high. That might mean a prolonged period of legislative deadlock with neither party able to solve the nation's problems, while those problems mount. The President will turn his attentions to foreign policy, where he can normally proceed without consulting Congress, and he will try to use the federal bureaucracy to do most of the work of domestic reform. This, in turn, will create ever greater incentives for Presidential unilateralism both in foreign and domestic policy, and increasing legislative irrelevance.

This second path has its own dangers. Let me put it bluntly: Either the Senate's rules are reformed soon, or Congress becomes increasingly irrelevant to governance. It must still pass appropriations bills, but it will be increasingly unable to direct domestic policy because neither party will be able to form supermajorities in favor of major policy changes. Earmarks and minor programs remain possible, but not major ones. And if Congress becomes irrelevant, the institution of the presidency is strengthened in the long run, whether or not Barack Obama wins reelection. If the President cannot reform Congress through political exertion, he is likely to strengthen his own ability to decide matters on his own. A strengthened Presidency moves us ever closer to rule by executive decision in American politics.

In other words, the current fight over the Senate, caused by bitter polarization in American politics, threatens the constitutional status of Congress as much as it does Barack Obama.

Earlier I noted that we have developed polarized parliamentary-style parties in a constitutional system not designed for parliamentary government. So if Congress cannot be reformed to become more parliamentary, perhaps the party system will dissolve and become more consistent with the constitutional structures we do have. Perhaps the political parties will become less polarized and less ideologically cohesive. I would not bet on this possibility happening in the short run, however. Our current political polarization is supported by many features of American politics, including the primary system, first-past-the-post rules in elections, and our current system of campaign finance.

If you think American politics was interesting the past year, just wait until you see the next three. Difficult and dangerous times are ahead for the republic.